The man, identified as Martin Gugino, seen walking towards a line of police officers in riot gear advancing forward.
As he gestured to one of the cops, others yelled for him to move back. They listen to him for 30 second and was pushed in the chest, knocking him over backward.
One officer appeared to call the ambulance for assistance. Two officers were suspended.
Fifty-seven officers resigned in disgust because of the treatment of two of their members, who were simply executing orders," Buffalo Police Benevolent Association president John Evans told WGRZ.
Mayor Byron Brown said he wants the two suspended officers to get due process. "I am not calling for them to be fired."
Speaking of the injured man, the mayor said, "He was asked to leave numerous times last night."
Police felt that it was important to clear the area before fights broke out among the protesters, the mayor said. He stressed that the instructions from the police managers to officers was to be careful, protect residents and use common sense.